1. Field of the Invention
This invention relates to a film feeder for use in an automatic developing machine and, more particularly to, a film feeder for use in an automatic developing machine in which a film is withdrawn from a film cartridge and the thus drawn film is fed to an automatic developing machine that automatically processes the film while conveying the same utilizing a power supply from a utility power source.
2. Related Background Art
In an automatic developing machine, a film withdrawn from a film cartridge is conveyed so as to undergo developing, bleaching, fixing, and rinsing treatments in sequence. The film is conveyed using sprockets which engage with perforations formed at predetermined intervals in a leader attached to the leading end of the film. The tail end of the film coiled around the film cartridge is affixed to a spool in the film cartridge, and hence the film becomes tensioned immediately before being completely withdrawn from the film cartridge. The automatic developing machine detects the tail end of the film by sensing the tensioned state of the film using a sensor, and actuates a cutter so as to cut the film in the vicinity of its tail end portion.
As is the case with an ordinary household, the previously mentioned automatic developing machine receives a power supply from an electric-power company. For this reason, in the event of a power failure, the drive system of the developing machine stops, and the film remains immersed in whichever processing bath, thereby resulting in damage to the film. To avoid such a trouble, it is necessary to discharge the film from the automatic developing machine.
In such a case, the film is conveyed manually using a handle, and the tail end region of the film is cut by manually actuating the cutter. Thereafter, the film is removed from the automatic developing machine. Thus, a very laborious operation was needed to remove the film from the automatic developing machine.
To reduce the burden on an operator when the film is taken out of the automatic developing machine, a film feeder for use in an automatic developing machine disclosed in Unexamined Japanese Patent Laid-Open No. 4(1992)-78852 (corresponding to U.S. Pat. No. 5,250,974) has been proposed. Specifically, in this film feeder, a capacitor is charged by electrical energy fed from a utility power supply circuit during normal feeding conditions. In the event of a power failure, switching means switches the supply of electrical energy from the utility power source circuit to the capacitor, and the cutter is actuated by this electrical energy so as to cut the film.
In this conventional configuration, the cutter is actuated using the electrical energy supplied from the utility power supply circuit during normal feeding conditions. In contrast, in the event of a power failure, the cutter is actuated using the electrical energy discharged from the capacitor as a result of switching action of switching means. In this way, the conventional apparatus requires switching means, which complicates a circuit configuration.